#!/usr/bin/env python3
from cv2 import (
    THRESH_BINARY, ADAPTIVE_THRESH_MEAN_C,
    adaptiveThreshold as adaptive_threshold, calcHist as calc_hist, blur,
    equalizeHist as equalize_hist, GaussianBlur as gaussian_blur,
    imread, imshow, Laplacian as laplacian, medianBlur as median_blur,
    resize, Sobel as sobel, threshold, waitKey as wait_key)
from numpy import uint8

FILENAME = 'dino-gang.jpg'
GREYSCALE_COEFF = 0.2126, 0.7152, 0.0722
THRESHOLD, WHITE = 128, 255
BLUR_KSIZE = 6, 9


def disp(image, name):
    """Display the given image."""
    imshow(name, image.astype(uint8))
    wait_key()


# Exercise 1
image = imread(FILENAME)
disp(image, 'original')

# Exercise 2
disp(resize(image, (512, 512)), 'square')

# Exercise 3
# I'm going to ignore about cv2.IMREAD_GRAYSCALE
grey_image = uint8(image.dot(GREYSCALE_COEFF))
disp(grey_image, 'grey')

# Exercise 4
a, b = 1/2, 1/3
disp(image*a+b, 'brightness adjusted')

# Exercise 5
disp(threshold(grey_image, THRESHOLD, WHITE, THRESH_BINARY)[-1],
     'binary threshold')
disp(adaptive_threshold(grey_image, WHITE, ADAPTIVE_THRESH_MEAN_C,
                        THRESH_BINARY, 25, 12), 'adaptive threshold')

# Exercise 6
hist = calc_hist([grey_image], [0], None, [256], [0, 256])
disp(equalize_hist(grey_image), 'equalized')

# Exercise 7
disp(blur(image, BLUR_KSIZE), 'blur')
disp(gaussian_blur(image, (0, 0), 5), 'Gaussian blur')
disp(median_blur(image, 7), 'median blur')

# Exercise 8
disp(laplacian(image, 2), 'Laplacian')
disp(sobel(image, 2, 1, 1), 'Sobel')